This invention relates to a brake condition indicator, and more particularly, to means for providing a visual warning to the driver of the vehicle when the brake system in that vehicle is in danger of becoming inoperative due to overheating, excessive use, or the like.
Heretofore, devices have been proposed which provide structure for indicating abnormalities in the operation of brakes in trains and other vehicles. In fact, patents have issued on such suggestions including U.S. Pat. No. 1,907,540 for a temperature indicator applied to railway cars. In addition, Pat. No. 1,957,051 suggests a brake temperature indicator for vehicles, and U.S. Pat. No. 3,975,706 provides an abnormality detector device in a brake system. Also, U.S. Pat. Nos. 2,494,269, 3,321,045, 3,689,880, 3,634,840, and 3,510,835 disclose sensing devices to indicate the condition of brakes on vehicles. However, the structure suggested by these patents of the prior art are quite complex and require that the brake system in the vehicle be modified during construction of the vehicle in order to accommodate the sensing means. There is no suggestion of the utilization of standard, conventional brake systems with such devices, but instead specially built constructions are required. For example, U.S. Pat. No. 1,957,051 discloses thermo elements fitted within a bushing which is secured to the brake shoe. The bushing operates in a slot in a briefing plate. U.S. Pat. No. 3,975,706 provides such a complex system incorporating casings of phenolic resin provided with pick-up coils having a magnetic core which is permanently attached to the system during its manufacture. The other patents mentioned above embody concepts which are expensive and complicated and which are also specially built during the manufacture of the vehicle. Conventional brake arrangements must therefore be modified with the consequent great expense in production, repair, and replacement. Furthermore, the conventional brake shoe is produced of asbestos or similar material and attempts to secure the head detecting devices thereto have been unsuccessful in that the slightest ingression by conventional sharp edged instruments will split, fracture, or otherwise cause damage to the brake shoe itself.